package leetcode.editor.cn;

import leetcode.editor.cn.common.ListNode;

/**
 * @Author: Dempsey
 * @Data: 2021-03-11 20:36:55
 */

//反转一个单链表。 
//
// 示例: 
//
// 输入: 1->2->3->4->5->NULL
//输出: 5->4->3->2->1->NULL 
//
// 进阶: 
//你可以迭代或递归地反转链表。你能否用两种方法解决这道题？ 
// Related Topics 链表 
// 👍 1568 👎 0


public class P206 {
    public static void main(String[] args) {
        Solution solution = new P206().new Solution();
        int[] a = {1, 2, 3, 4, 5};
        ListNode head = ListNode.getListNodeByArray(a);
        solution.reverseList(head);
        System.out.println(head);
    }

//leetcode submit region begin(Prohibit modification and deletion)

    /**
     * Definition for singly-linked list.
     * public class ListNode {
     * int val;
     * ListNode next;
     * ListNode() {}
     * ListNode(int val) { this.val = val; }
     * ListNode(int val, ListNode next) { this.val = val; this.next = next; }
     * }
     */
    class Solution {
        public ListNode reverseList(ListNode head) {

            ListNode prev = null;
            ListNode curr = head;

            while (curr != null) {
                ListNode nextTemp = curr.next;
                curr.next = prev;
                prev = curr;
                curr = nextTemp;
            }

            return prev;

        }
    }
//leetcode submit region end(Prohibit modification and deletion)

}